Achieving Ultra-High Reliability for Emerging Applications in Future Wireless Systems

Wireless communication systems have been evolving since the first generation. With the fifth generation (5G) of wireless systems, the focus is not only on the evolutionary aspect of increased data rate, but also on novel performance metrics for emerging applications, such as autonomous driving, industrial automation, and Tactile Internet applications. In this context, the wireless system design has increasingly turned its focus on guaranteeing extremely high reliability and low latency.  Hence, the developments of 5G systems require leveraging novel techniques to cope with the heterogeneity of applications and to achieve their stringent requirements.

This talk focuses on the definition of reliability in wireless systems and on fundamental techniques to achieve reliability requirements in 5G networks. Firstly, definitions and concepts of reliability theory, which provides a mathematical tool to evaluate and improve the reliability and availability of technical components and systems, are applied and extended to wireless networks. Then, the signal-to-interference-plus-noise ratio (SINR) is identified as a major metric to study the impact of the wireless link quality on high availability. For addressing new requirements imposed on emerging 5G applications, e.g. outage probabilities of 10-7 or less, a highly accurate modelling of the SINR is needed. A stochastic model of the SINR including the shadow fading, noise power, and best server policy is presented as an alternative to highly complex wireless system simulations providing extreme accuracy and a tool to evaluate the outage probability at any position in any given wireless network. As diversity techniques, such as multi-point connectivity which are also supported by the 5G systems, are widely accepted to be key to achieve high reliability, the proposed SINR model is extended to multi-point transmission. Numerical evaluations reveal the applicability of the model to multi-point connectivity. However, unlike the general understanding, it will be shown that ensuring low outage probabilities does not necessarily imply improved reliability in multi-user systems, in which resources are shared. In this regard, a novel matching theory-based algorithm aiming for guaranteeing reliability requirements in a multi-cellular, multi-user system will be presented. The proposed algorithm yields a maximum gain of 150% as compared to fixed multi-point approaches. The talk will be concluded with a research vision for how the results obtained so far can be extended to design highly flexible and autonomous tools for investigating future wireless systems, which simultaneously support multiple services with diverse requirements. These tools will open the new era for studying the feasibility of emerging applications under given conditions and the coexistence of various use cases with diverse and (partially) competing requirements, for developing novel concepts and end-to-end solutions for intelligent and predictive resource management in wireless systems, and for applying and implementing these concepts and solutions into real systems.